Endless ribbon cartridge



' ENDLESS RIBS-0H CARTRIDGE Filed Oct. 24, 1968 2 Sheets-Sheet l PIERRE J. GREENE JOSEPH 0. SBARRA Aug; 18, 1970 P. J. GREENE ENDLESS RIBBON cmiwnmcn 2 Sheets-Sheet 8 Filed Oct. 24, 1968 FIG. 6

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United States Patent O F 3,524,602 ENDLESS RIBBON CARTRIDGE Pierre J. Greene, Apalachin, N.Y., and Joseph D. Sbarra, Hightstown, N.J., assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed Oct. 24, 1968, Ser. No. 770,252 Int. Cl. B65h 17/48 US. Cl. 24255.19 6 Claims ABSTRACT OF THE DISCLOSURE The cartridge comprises an endless ribbon that exits through the hollow core of a spool and after passing a work station is suitably driven back into the cartridge and rewound upon itself. A leaf spring or a spring-biased element bears against the innermost convolution of the ribbon to maintain output tension within predetermined limits; i.e., as ribbon tension increases, the spring or element yields inwardly toward the spool to reduce tension between the convolutions, and as ribbon tension decreases, the spring or element flexes outwardly to increase the tension.

This invention relates to endless ribbon cartridges, and more particularly to those embodying means for automatically controlling tension on the ribbon within predetermined minimum and maximum limits.

BACKGROUND OF INVENTION It is, of course, known to provide a cartridge comprising an endless ribbon or tape that is wound on a hollow spool or core and exits through a slot in the spool, passes a work station, and then re-enters the cartridge to form the outermost convolution of the wound coil. It is also known, for example from U.S. Pat. 3,126,163, to provide a relatively complex, manually adjustable tape tensioning member which exerts a bias force on the ribbon after it is withdrawn from the spool and while it is at the work station. And US. Pat. 2,921,787 discloses a stationary sheet metal spring clip having an integral curved spring finger that is bent to conform generally to the shape of the hub or of the innermost convolution and projects between this and the adjacent convolution, but this finger merely serves to facilitate peeling 01f of the tape from the innermost wrap of the coil, and thus guides it. Neither of these patented arrangements provide any output tension control for the tape or ribbon.

There is a need for a simple, compact, relatively inexpensive endless ribbon cartridge wherein output tension of the tape is automatically maintained within predetermined limits to facilitate unwinding and rewinding of a mechanically driven endless ribbon.

SUMMARY OF INVENTION Toward this end, and according to the invention, there is provided a cartridge comprising base and cover portions with concentric snugly fitting hollow rims that define a spool around which an endless ribbon is wound. The innermost convolution of the ribbon .exits through slits in both rims and thence via the hollow spool core, passes a work station and then is driven back into the housing to constitute the outermost convolution. A resilient means, such as a leaf spring, projects against the innermost convolution to exert a bias force thereon. As output tension on the ribbon increases and decreases relative to a desired nominal amount, the resilient means will yield or flex as necessary to tend to maintain the tension within a preselected range.

Other features, objects and advantages will become apparent from the following more detailed description of the invention and from the accompanying drawings, wherein:

3,524,602 Patented Aug. 18, 1970 FIG. 1 is a plan view of an assembled endless ribbon cartridge constructed according to the preferred embodiment of the invention;

FIG. 2 is a plan view of a base forming one part of the housing for the cartridge of FIG. 1;

FIG. 3 is a bottom plan view of a cover forming the remaining part of said cartridge housing;

FIG. 4 is a perspective view of a leaf spring embodied in the cartridge of FIG. 1;

FIG. 5 is a horizontal section view of the assembled cartridge of FIG. 1;

FIG. 6 is an end view of the top end of the cartridge of FIG. 1;

FIG. 7 is a vertical section view taken along the line 77 of FIG. 1;

FIG. 8 is a plan view of a base forming part of a cartridge constructed according to another embodiment of the invention; and

FIG. 9 is a horizontal section view of an assembled cartridge constructed according to said other embodiment.

DESCRIPTION As illustrated in FIGS. 1 to 7, the endless ribbon cartridge according to its preferred embodiment comprises a housing consisting of a base 10 and a cover 11; an endless inked ribbon 12 for a typewriter or the like; and a leaf spring 13. Base 10 comprises a relatively flat portion 14 having an inverted T-shaped aperture 15 surrounded by a rectangular boss 16, and an upstanding circular rim 17 that surrounds said boss. The rim 17 has a slot 18 extending obliquely downward from its upper surface and a vertical slit 19 through which the leaf spring 13 ca" extend.

The cover 11 comprises a substantially flat portion 20 having a circular aperture 21 encircled by a downwardly extending rim 22 that fits snugly and concentrically within the upstanding rim 17 of the base. Rim 22 has a wide slot 23 that is adapted to straddle the oblique slot 18 when the cover is assembled to the base. Formed integrally with each of the four edges of fiat portion 20 are downwardly extending flanges 24, 25, 26, 27, respectively. An entry slot 28 extends obliquely upward from the bottom of flange 24 to provide an aperture through which the endless ribbon 12 is driven into the cartridge by suitable means (not shown). Each flange 24 to 27 preferably has a recess 29 f6r receiving a corresponding one of four tabs 30 that project outwardly from the flat portion 14 of the base to constitute a means whereby the cover may be assembled to the base through snap-fit engagement. Reinforcing ribs like 31, preferably are formed in the portion 22 and radiate from the rim 22 to the flanges 24-27.

As best shown in FIG. 5, the endless ribbon 12 is coiled around the rim 17 of the base. When the cartridge is assembled, rims 17 and 22 of the base and cover combine to constitute a spool; and as best shown in FIG. 7, one end of this spool is partially blocked by flat portion 14, but the other end of the spool is completely open. As shown in FIG. 5, the innermost convolution of ribbon 12 exits through the spool via oblique slot 18 in outer rim 17 and the wide slot 23 in inner rim 22. It is then guided by suitable means (not shown) past a work station, such as a printing station, and then when within six inches of the cartridge is driven, such as by a drive roll (not shown), back into the cartridge through slot 28 in the cover to constitute the outermost convolution of the coiled ribbon.

According to an important feature of the invention, the output tension on the ribbon is automatically controlled with preselected minimum and maximum limits by the leaf spring 13. As best shown in FIG. 4, leaf spring 13 has an anchor portion 32 that rests flush against the inner surface of base rim 17 (see FIG. 2); and the spring has an integrally formed curved portion 33 that extends through the slit 19 and bears against the innermost convolution of the ribbon 12, as best shown in FIG. 5. By insertion of the rim 22 of the cover into the rim 17 of the base, the spring portion 32 is clamped between rims 17, 22 and the ribbon coil is concurrently enclosed within the cartridge housing 10, 11. As earlier noted, the cover and base are maintained assembled by the snap-fit engagement of tabs 30 within recess 29.

With spring portion 32 thus anchored, the curved portion 33 exerts a bias force on the innermost convolution of the ribbon coil by distending a small part of the inner core of the coil. Since the spring 13 is of flexible or resilient material, it is capable of flexing inwardly and outwardly; i.e., toward and away from the rims. As output tension on the ribbon increases above a preselected value, the curved flexible portion 33 of spring 13 will yield toward the rims 17, 22, thus tending to relieve the strain and binding action on the ribbon to reduce the output tension. Conversely, if the output tension should tend to become too low, the spring portion 33 will flex away from the rims 17, 22, to increase output tension on the ribbon. Thus, the spring portion 33 normally will be flexed inwardly somewhat from its freestate position, in which it is shown in FIG. 4, so that it may flex outwardly as well as inwardly and thus act to maintain the output tension within a preselected range.

From the foregoing, it will be apparent that the degree of flexibility or stiffness of the spring 13 must be preselected to provide the desired bias force for the particular controlling parameters involved, notably the length and inherent stiffness of the ribbon, the length of the ribbon path outside the cartridge, the number of convolutions of ribbon and location of the spring 13 from the exit slot of the cartridge. Variation in any one of these parameters or of the stiffness of spring 13 will affect the output tension and/or the ribbon take-up. For example, if the length of the ribbon 12 is increased while all other parameters are maintained unchanged, the output tension will decrease and the ribbon take-up will be slightly retarded. Conversely, if the length of the ribbon path is increased while all other parameters are maintained unchanged, the output tension will increase and the ribbon take-up will be slightly improved. As the number of convolutions of ribbon is increased, output tension will increase and ribbon take-up will be improved. Also, as spring 12 becomes stifi'er, the output tension will increase and the take-up will be improved.

It has been found by actual test that the optimum condition exists when the output tension is low (of the order of 4 to 6 ounces) and the take-up is sufficient so that no slack appears as the ribbon re-enters the housing.

The inverted T-shaped slot is preferably provided to facilitate rapid mounting of the cartridge on a support (not shown). For example, as best shown in FIG. 7, the cartridge would be mounted with the base against the support by moving the housing 10, 11 rightward, inserting a support lug through the wide base of the slot 15,

Y and then moving the housing downward relative to the lug so the housing will be retained between the lug and the remaining portion of the support, by contact of the lug with the boss 16 above the wide part of the slot.

Except in the respects hereinafter noted, the embodiment according to FIGS. 8 and 9 is identical in all material respects with that of FIGS. 1 to 7; and hence like reference numerals, but primed, will be used to denote parts which are similar to those of the preferred embodiment. Secured to base 10', as by screws, within rim 17' is a seat 50 for a helical spring 51. Spring 51. biases a plunger 52 radially outward from the axis of the concentric rims 17', 22' and through relatively wide aligned slots 53, 54, in said rims, respectively. The spring-biased plunger 52 exerts a bias force on the innermost convolution of coiled ribbon 12 of a magnitude and for the same purpose as the leaf spring 12 of the preferred embodiment. The cartridge is mounted to a support (not shown) by inserting a threaded support shaft through a bore 55 in base 10' and then screwing an internally threaded collar over the shaft into flush engagement with a boss 56 encircling bore 55.

It will be apparent that the foregoing and other changes may be made without departing from the spirit, scope and teaching of the present invention. Accordingly, the cartridge herein disclosed is to be considered merely as illustrative, and the scope of the invention is to be limited only as specified in the claims.

What is claimed is:

1. A cartridge comprising an endless ribbon,

a housing providing,

a hollow spool means about which the ribbon is convoluted and a slit through which the innermost convolution of the ribbon exits, and

a slot into and through which the ribbon is driven to become the outermost convolution, and

resilient means extending outwardly from the spool means to exert on a portion of the innermost convolution of ribbon a bias force of a magnitude preselected to maintain output tension on the ribbon within predetermined limits by operating to reduce the bias force as tension increases and increase the bias force as tension decreases. I

2. A cartridge according to claim 1, Where the resilient means comprises a leaf spring, the inner portion of which is retained by the spool means, and the outer portion of which flexibly bears against the innermost convolution of the ribbon.

3. A cartridge according to claim 1, wherein said housing comprises two parts providing respective hollow rims that fit snugly and concentrically together to constitute the spool means.

4. A cartridge according to claim 3, wherein said resilient means comprises a leaf spring having one portion that is clampingly retained between the ad- ,jacent surfaces of said rims and another portion that projects through an opening in the outer one of said rims and flexibly bears against the innermost convolution of the ribbon.

5. A cartridge according to claim 1, wherein said housing comprises a base having an upstanding hollow rim,

a cover having a hollow rim that fits snugly and concentrically within said upstanding rim, and

means providing a snap fit attachment for the cover to the base, and wherein said cover provides the slot and said spool means is defined by said rims.

6. A cartridge according to claim 1, wherein the resilient means comprises a spring seated against a part of said housing means, and a plunger extending in a substantially radial direction through said spool means and biased by said spring into contact with the said portion of the innermost convolution.

References Cited UNITED STATES PATENTS 6/ 1960 Nygaard 242-5539 5/1962 Pieplow et a1. 24271.1 XR 10/1966 Krueger et a1 242-55.53 7/1967 Batlas et a1. 242-5553 FOREIGN PATENTS 12/1928 France.

US. Cl. X.R. 

